Along with the rapid development of information technology and semiconductor technology, a thin film transistor liquid crystal display (TFT-LCD), which has such advantages as high display quality, high space utilization, low power consumption, no radiation and small volume, has been widely used. Since the human eyes' ability to identify brightness is not linear, Radio Frequency Signal Electronics Standards Institute has made a curve with a gamma value of 2.2 in accordance with the human eyes' characteristics, so as to facilitate the grayscale adjustment by a TFT-LCD designer, thereby to enable the TFT-LCD to present an image that is more suitable to the human visual characteristics.
Currently, there are mainly two methods for calibrating the gamma curve. 1) The accurate color capture (ACC) of a timing controller (TCON) may be adjusted so as to adjust a grayscale voltage across an LCD module (LCM) and test a grayscale-transmittance curve of the LCM, thereby to adjust a gamma value of the LCM. For this method, it is convenient to adjust the grayscale voltage across the LCM by adjusting the ACC of the TCON, but the adjustment range is limited and needs support from the manufacturers. As a result, it is adverse to the rapid development of the product, and the adjustment efficiency is low. 2) The divider resistance of several gamma voltages applied externally may be adjusted, so as to change the grayscale voltage across the LCM and test the grayscale-transmittance curve of the LCM, thereby to adjust the gamma value of the LCM. For this method, the LCM may be developed quickly by the original manufacturer, but due to the plurality of gamma voltages applied externally, it is very complex to adjust the resistance and the adjustment efficiency is low.